2± J. H. Gore — Decimal System of Seventeenth Century. 



author has exhibited in treating of them, and also the industry 

 and labor of twelve years, which he bore with an unwearied 

 mind, for the sake of the truth that was to be attained. 

 Indeed, T have such confidence in these observations, that I 

 would regard my own, if I had any, as inferior to them ; but 

 hitherto I have been unable to accomplish anything in this 

 subject, although I am very fond of such things. Mouton's 

 estimate of Eiccioli' s work was far above its deserts, perhaps 

 owing to the fact that they were friends and closely nnited by 

 religious ties. An examination of Eiccioli's arc measurement 

 shows that his base was very short, that only two angles of each 

 triangle were observed, that many of the angles were small, 

 that some were determined indirectly as sums or differences of 

 other angles, that no corrections were made for refraction and 

 that some distances were estimated from meandered lines. 

 Hence we are prepared for an erroneous result — 62,650 toises 

 for a degree. Sn ell's result was far superior, but was most 

 likely unknown to Mouton — as the work published in Leyden 

 would with difficulty reach Lyons, nor did the discussions of 

 Munschenbroek and Cassini appear until many years after. So 

 all the observations, ancient as well as modern, were represented 

 on the modern side by those of Eiccioli, Fernel and probably 

 Xorwood, as Picard had not at this time begun his labors. 

 Our Metrologist went still further, not being satisfied with 

 merely suggesting a system, he gave the length of his unit in 

 terms of other measures. Eiccioli gave his degree length in 

 terms of the Bologna foot, and also in terms of the old Eoman 

 foot. This furnished ]\Iouton a check as he had the ratio of 

 the French foot to both ; the two reductions were harmonious, 

 justifying his belief that we cannot be ignorant of the true 

 length of the virga and the virgula, which in comparison with 

 the other geometrical measures are easily attained ; and for the 

 sake of this length, "we must test and observe many things, 

 that will be not a little useful for the preservation of these 

 measures." In reading this, one would hardly imagine that the 

 pendulum principle discovered only a few years before this— 

 though not published until eight years later, was referred to, 

 and that Mouton had in mind the second's pendulum as the 

 best means of preserving and transmitting his standard ; yet 

 this was the case, as we shall see from what follows : " A 

 geometrical virgula is exactly equal to a pendulum which 

 makes 2959 -2 single vibrations in half an hour, as we shall 

 show by means of many experiments, used for this purpose, 

 through which we endeavor to show the length of the virga 

 and virgula, a thing to be known by all others wishing to 

 obtain it. 



